change background color of certain sections like example (Tripod)

The main page background is white, but several of your sections have a gray background just for that section that spans the width, but doesn't change that background of the entire page.

I do see in the sample blog it says there is Advanced Styling to change the colors but I must be blind because I have looked all over for it! I have looked in Styling and all I have is select body background where I can choose an image for the background from the grid,